Reactance-coil.



UNITED STATES Patented June 14, I904.

PATENT OEEicE.

JOHN J. FRANK, OF SCHENEOTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEIV YORK.

REACTANCE-COIL.

SPECIFICATION forming part of Letters Patent No. 762,697, dated June 14,1904.

Application filed October 16, 1902. Serial No. 127,455. (No model.)

To all whom it may concern.-

Be it known that I, J OHN J. FRANK, a citizen of the United States,residing at Schenectady, in the county of Schenectady, State of NewYork, have invented certain new and useful Improvements inReactance-Ooils, of which the following is a specification. v

Heretofore reactance-coils have been constructed in which a highreluctancewas obtained by forming relatively large air-gaps in themagnetic circuit. In one form of reactance-coil which has been employedthe core is substantially a cylinder, and the lines of force have anair-path from one end of the cylinder to the other. Among other formswhich have been used are those in which the core is shaped like theletters U and E. These forms of cores have all been open to theobjeetion that the leakage or stray field was of considerable magnitude,and with reactancecoils of large capacity this stray field is of suchmagnitude that no metal casing can be employed near or around the coilowing to the heating effect induced therein by the stray field. Vithlarge reactanee-coils having a large stray field another difiiculty metwith lies in the fact that it is impossible to place them on a floorsupported by steel or iron girders owing to the heat effect produced inthe girders by the eddy-currents which result from thestray field; norcan any large body of unlaminated metal be placed near suchreactance-coils without injurious results.

In a reactance-coil constructed in accordance with my invention thenecessary reluctance is obtained by forming a plurality of smallair-gaps in the magnetic circuit. By this means the reluctance of themagnetic circuit may be increased to a considerable extent, while at thesame time the absence of any one large air-gap reduces the tendency tothe creation of a large stray field.

For a better understanding of my invention reference may be had to theaccompanying drawings, in which I have illustrated forms of myinvention.

Figure 1 is a plan view, partly broken away and partly in section. Fig.2 is a sectional elevation taken on the line 2 2 of Fig. 1. Fig. 3 is aplan view showing one form of lamina employed, while Fig. 4 shows adifferent form.

In the drawings, 1 represents a base upon which is mounted a three-phaseair-cooled reactance-coil. Upon lugs 2, formed upon the inner side ofthe base, are mounted members 3, which in turn support members 4:, uponwhich the core of the reactance-coil is placed. The core of thereactance-coil consists of groups of laminae 5, the groupsbeingseparated from one another, as shown, to form suitableventilating-spaces 5. Each separate lamina is a punching formed from oneintegral piece of material and having three pairs of openings 7, inwhich the the three sets of windings of the three-phase system can beplaced. The laminae are separated from the member 4: by pieces of woodor other suitable insulating material 8. Blocks 9, similar to the blocks8, are placed on top of the core to 7 separate the core from the topmember 10 of the casing.

In assembling the laminae alinement is secured by means of wooden pinswhich are placed in the openings 6, formed in the corepunehings. Whenthe parts are assembled, the core is clamped between the members 4: and10 by means of bolts 11. Each of the channels formed by the successiveopenings 7 is lined with insulating material 12, and in these linedchannels are placed conductors 13.

The conductors 13 consist of U shaped strips of copper which areinserted from the top and are connected together at the bottom 7 bycross-bars 14:, which are soldered to and 5 connect opposite sides ofadjacent U-bars. The conductors are spaced apart, as shown in Fig. 1, inorder that the air may circulate between them. I have not thought itnecessaryillustrate the spacing-blocks employed. Suit- 9 able terminals15 lead from the opposite ends of each coil thus formed. Blocks ofWood16 and 17 are employed to position the connecting-strips 1 1 andterminals 15. A removable cover 17 rests in the opening 18, formed in 9the upper side of the member 10. A suitable casing 19, preferably ofsheet metal, surrounds the core of thetransformer extending from themember 10 to the base member 1.

This reactance-coil is intended to be placed) over a fan-chamber and tohave air forced or drawn through the coils and core parts in order tocool it.

In Fig. 3 of the drawings I have shown the form of punching which Iprefer to employ in the construction of these reactance-coils. Aplurality of comparatively small oblong slots or perforations are formedin that portion of the core which is surrounded by the winding. Theseslots are quite narrow and are placed with their longest dimension atright angles to the path of the magnetic flux. In this figure I haveshown these openings or air-gaps formed in rows, with the air-gaps insuccessive rows breaking joints with one another. By this arrangementthe reluctance in the magnetic circuit is increased, while at the sametime a core is obtained which is mechanically strong and in which byreason of the distribution of the air-gaps the tendency to the creationof a stray field is comparatively small. By reason of the smallness ofthe air-gaps and their arrangement and by reason of the narrowness ofthe necks connecting the air-gaps the most of the flux will pass throughthe air-gaps, and the local heating at the edges of the air-gap will beslight. Moreover, as the punchings are similar the air-gaps insuccessive laminae register with one another and form channels, throughwhich the air can circulate and carry oif heat generated therein.

In Fig. 4 I have shown a modified form of punching in which the air-gapsare of the same general dimension as those shown in Fig. 3; but those insuccessive rows are not staggered with respect to one another.

While I have shown my invention as embodied in a three-phase air-cooledreactancecoil, Ido not consider it in its broader aspect as limitedthereto. For instance, my inven tion can be applied to a single-phasereactance-coil or to a multiphase reactance-coil other than that shownor, indeed, in many cases Where amagnetie circuit possessing theadvantages of those described is desired. It is not essential that themagnetic circuit be of the so-called shell type shown, as the inventioncan be applied to other types, the particular form of the magneticcircuit being in general immaterial; neither is it essential that eachlayer or lamina be formed of one integral piece as a core in which eachls eris formed of several pieces and could also be provided with myinvention.

While I have shown my invention as applied to an air-cooledreactance-coil, meaning one in which artificial means are employed toforce air through the reactance-coil, it is obvious that a core havingits reluctance increased by the formation of the small gaps in themagnetic circuit could be employed in a reactancecoil of the oil-cooledtype or in one in which no artificial means for cooling the reactance-COIl are provided. IVhere in the claims I have used the term air-gap, Ido not intend to exclude those reactance-coils in which this gap may befilled with oil or other dielectric, as I consider that such forms arefull equivalents of the air-gaps shown and described in my case. It isobvious that other arrangements of the case. the winding, &c., could beemployed without departing from the spirit of my invention.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In a three-phase reactance-coil having a laminated core, laminae eachconsisting of a single piece of material having three pairs ofconductor-receiving openings formed therein and having formed betweeneach pair of said openings a plurality of small distributed airgaps.

2. A fluid-cooled reactance-coil having a laminated core and havingair-gaps formed in the lamina: to increase the magnetic reluctance, theair-gaps in successive laminae registering with each other to formchannels or passages through which the cooling fluid may pass.

3. In combination, a laminated magnetic core, and means for producing amagnetic flux therein, each lamina of said core having a plurality ofsmall air-gaps formed therein and arranged in rows extendingtransversely to the direction of the magnetic flux.

4:- In combination, a magnetic core made up of laminae, and means forproducingamagnetic flux therein, each lamina of said core being providedwith a plurality of comparatively small air-gaps arranged in rowsextending transversely to the direction of the magnetic flux and withthe air-gaps in one row breaking joints with those in adjacent rows.

5. In a reactance-coil, the combination with the windings, of a coreconsisting of iron sheets having a plurality of short air-gapsdistributed laterally and longitudinally along the sheets to obtain therequisite reluctance in the magnetic circuit.

6. In a reactance-coil a core comprising laminae having a plurality ofsmall air-gaps distributed over a considerable portion of their extent,and a magnetizing-coil therefor.

7. A magnetic core havinga perforated portion and an unperforatedportion, and means for generating a magnetic flux passing substantiallyentirely in series through said perforated portion and through saidunperforated portion.

8. In combination, a magnetic core comprising a perforated portion andan-unperforated portion and a magnetizing-winding surrounding saidperforated portion.

In witness whereof I have hereunto set my hand this 15th day of October,1902.

JOHN J. FRANK.

WVitnesses:

BENJAMIN B. HULL, HELEN ORFORD.

